1. Field of the Invention
This invention relates to a bulb socket that is able to prevent the erroneous insertion of a light bulb.
2. Description of Related Art
An example of a light bulb socket has been disclosed by Japanese Unexamined Patent Application No. 131089/1991. The light bulb socket is formed with a socket body of synthetic resin. One end portion of the socket body is formed into a connector section to which a mating connector is connected and the other end portion has a bulb engaging hole with which a light bulb is engaged. In order to fixedly insert contactors in the bulb engaging hole, a pair of contactor inserting grooves is formed in the inner cylindrical surface of the bulb engaging hole so that the grooves are axially extended and diametrically opposed to each other. In addition, a pair of bulb inserting grooves is formed in the inner cylindrical surface of the bulb engaging hole in such a manner that the bulb inserting grooves are angularly shifted from the contactor inserting grooves and diametrically opposed to each other. The bulb inserting grooves are so-called "J-slots" that receive locking pins extending from the bulb base. Each of the bulb inserting grooves includes a guide portion that is axially extended and a locking portion that is extended laterally from the deep end of the guide portion.
The light bulb is connected to the socket in the following manner. First, the contactors are fixedly inserted into the bulb engaging hole through the contactor inserting grooves. Next, the bulb base is inserted into the bulb engaging hole with its locking pins set at the inlets of the bulb inserting grooves. When in this position, the light bulb is turned slightly until the locking pins are engaged with the locking portions of the bulb inserting grooves. Thus, the bulb is prevented from coming off the socket, while the bulb base is engaged with the contactors. The light bulb is thereby fixedly and electrically connected to the bulb socket.
The above-described conventional light bulb socket suffers from several difficulties. In inserting the bulb base into the bulb engaging hole, frequently the locking pins of the base are erroneously inserted into the contactor inserting grooves. In this instance, the light bulb is not correctly connected to the socket and the electrical connection of the bulb base to the contactors is unsatisfactory. Since the locking pins are not locked, the bulb may drop from the socket when vibrated or otherwise disturbed.